1. Field of the Invention
The present invention relates to wireless communication systems, in particular, to an antenna and communications subsystem that may be used on passenger vehicles.
2. Discussion of Related Art
Many communication systems involve reception of an information signal from a satellite. Conventional systems have used many types of antennas to receive the signal from the satellite, such as Rotman lenses, Luneberg lenses, dish antennas or phased arrays. However, each of these systems may suffer from limited field of view or low efficiency that limit their ability to receive satellite signals. In particular, these conventional systems may lack the performance required to receive satellite signals where either the signal strength is low or noise is high, for example, signals from low elevation satellites.
One measure of performance of a communication or antenna subsystem may be its gain versus noise temperature, or G/T. Conventional systems tend to have a G/T of approximately 9 or 10, which may often be insufficient to receive low elevation satellite signals or other weak/noisy signals. In addition, many conventional systems do not include any or sufficient polarization correction and therefore cross-polarized signal noise may interfere with the desired signal, preventing the system from properly receiving the desired signal.
There is therefore a need for an improved communication system, including an improved antenna system, that is able to receive weak signals or communication signals in adverse environments.